Jitter buffer management for power savings in a wireless communication device

ABSTRACT

A technique for jitter buffer management for improved power savings in a wireless communication device ( 100 ) includes defining ( 202 ) a jitter buffer threshold for the wireless communication device, determining ( 204 ) that an amount of packets in the jitter buffer falls below the threshold, sending a trigger ( 206 ) to obtain queued voice packets from an access point, downloading ( 208 ) queued voice packets from the access point, and adding ( 212 ) the voice packets from the access point to the jitter buffer in the wireless communication device ( 100 ).

FIELD OF THE DISCLOSURE

The present invention relates generally to jitter buffers for wirelesscommunication devices and more particularly to jitter buffer managementfor power savings in a wireless communication device.

BACKGROUND

In Voice-over-IP (VoIP) communication systems, such as in a Wi-Finetwork for example, a jitter buffer is a buffer in a receiver of a userdevice where voice packets can be received, stored and sent to the voiceprocessor in evenly spaced intervals. Jitter is a variation in packetarrival time, which can occur because of nature of Wi-Fi communicationnetworks, which have inherent intermittent delays. The jitter bufferpurposely delays the received packets in order to minimize delayvariations so that a user of the device experiences voice communicationswith very little latency. However, there is a problem with jitterbuffers in battery-operated devices, wherein to overcome theintermittent delay issues, it has been necessary for a user device tocontinually communicate with an access point to maintain a stream ofvoice packets, which uses significant transmitter, and receiver, powerresources. Although this is required when a battery-powered devices istransmitting voice packets, it can be a problem when the device is nottransmitting, and has sufficient packets in its input buffer.

A solution to the problem has been to use power save operating modes.One of these modes allows legacy user devices to go into a sleep modeand wake-up periodically to listen to an access point's beacon. The APbuffers packets for a particular device if the device is in sleep mode,and indicates the availability of pending packets in the beacon frame.The user device, when it wakes up, checks the beacon to see if there arepending packets for it. If not, the user device goes back to sleep.Otherwise, the user device polls the AP to retrieve the packets.However, this solution still requires a user device to regularly wake upquite often, even if there are no packets waiting for it, which wastespower.

Another solution is to use scheduled or unscheduled Automatic Power SaveDelivery, wherein a user device needs to send a trigger frame to the AP,to cause the AP to deliver packets to the user device. The user devicewill then receive and acknowledge voice packets sent from the AP untilthe end of a service period. However, in this solution the user devicewill continue to send trigger frames to the AP even if its jitter bufferis full, which wastes power.

Accordingly, there is a need for jitter buffer management for improvedpower savings in a wireless communication device.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, together with the detailed description below, are incorporated inand form part of the specification, and serve to further illustrateembodiments of concepts that include the claimed invention, and explainvarious principles and advantages of those embodiments.

FIG. 1 is a simplified block diagram of a system, in accordance with thepresent invention.

FIG. 2 is a flowchart of a method, in accordance with the presentinvention.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of embodiments of the present invention.

The apparatus and method components have been represented whereappropriate by conventional symbols in the drawings, showing only thosespecific details that are pertinent to understanding the embodiments ofthe present invention so as not to obscure the disclosure with detailsthat will be readily apparent to those of ordinary skill in the arthaving the benefit of the description herein.

DETAILED DESCRIPTION

The present invention provides various jitter buffer managementtechniques for improved power savings in a wireless communicationdevice. In particular, a user device of the present invention only sendspolls or triggers for the AP to send voice packets when the jitterbuffer of the user device is nearing empty. As used herein, the term“voice” packets includes any packet used for audio purposes. It shouldalso be noted that the present invention is applicable to both staticand dynamic jitter buffers. This invention is also applicable to jitterbuffer management of video streams.

FIG. 1 is a block diagram depiction of a wireless communication network,including a wireless local-area network (WLAN) or other IEEE 802.11wireless communication system, such as a Wi-Fi network. However, itshould be recognized that the present invention is also applicable toother wireless communication systems. At present, standards bodies suchas OMA (Open Mobile Alliance), 3GPP (3rd Generation PartnershipProject), 3GPP2 (3rd Generation Partnership Project 2) and IEEE(Institute of Electrical and Electronics Engineers) 802 are developingstandards specifications for such wireless telecommunications systems.The communication system represents a system operable in a network thatmay be based on different wireless technologies. For example, thedescription that follows can apply to an access network that is IEEE802.xx-based, employing wireless technologies such as IEEE's 802.11,802.16, or 802.20, modified to implement embodiments of the presentinvention.

Referring to FIG. 1, there is shown a block diagram of an access point(AP) 102 and a user station (US) 100 adapted to support the inventiveconcepts of the present invention. Those skilled in the art willrecognize that FIG. 1 does not depict all of the network equipmentnecessary for system to operate but only those system components andlogical entities particularly relevant to the description of embodimentsherein. For example, an access point, eNodeB, or base station can beconnected with or comprise one or more devices such as wireless areanetwork stations, which include access nodes, Media Access Controllers,AP controllers, and/or switches), base transceiver stations, base sitecontrollers, packet control functions, packet control units, and/orradio network controllers. However, none of these other devices arespecifically shown in FIG. 1.

AP 102 is depicted in FIG. 1 as comprising a processor 118 coupled to atransceiver 116 and memory or storage device for a packet queue 120.User station 100 is depicted as comprising a processor 112 coupled to atransceiver 110 and jitter buffer 114 for packets received from the AP102. In general, components such as processors, memories, andtransceivers are well-known. For example, the transceivers as describedherein are operable to communicate together over an IEEE 802.11interface. In addition, processors are known to comprise basiccomponents such as, but not limited to, microprocessors,microcontrollers, memory cache, application-specific integratedcircuits, and/or logic circuitry. Such components are typically adaptedto implement algorithms and/or protocols that have been expressed usinghigh-level design languages or descriptions, expressed using computerinstructions, expressed using messaging logic flow diagrams.

Thus, given an algorithm, a logic flow, a messaging/signaling flow,and/or a protocol specification, those skilled in the art are aware ofthe many design and development techniques available to implement aprocessor that performs the given logic. Therefore, each of the AP 100and US 100 represents a known apparatus that has been adapted, inaccordance with the description herein, to implement various embodimentsof the present invention. Furthermore, those skilled in the art willrecognize that aspects of the present invention may be implemented inand across various physical components and none are necessarily limitedto single platform implementations. For example, the AP aspect of thepresent invention may be implemented in any of the devices listed aboveor distributed across such components. It is within the contemplation ofthe invention that the operating requirements of the present inventioncan be implemented in software, firmware or hardware, with the functionbeing implemented in a software processor (or a digital signalprocessor) being merely a preferred option.

User stations or remote unit platforms are known to refer to a widevariety of consumer electronic platforms such as mobile stations, mobileunits, mobile nodes, user equipment, subscriber equipment, subscriberstations, access terminals, remote terminals, terminal equipment,cordless handsets, gaming devices, personal computers, and personaldigital assistants, and the like, all referred to herein as userstations. Each user station comprises a processor that can be furthercoupled to a keypad, a speaker, a microphone, a display, and otherfeatures, as are known in the art and therefore not shown.

Referring back to FIG. 1, an access point (AP) 102 and user station (US)100 can be in the process of actively exchanging voice packets, as isknown in the art. In this type of typical operation, the processor 112will direct the US transceiver 110 to transmit a voice packet, whichstarts a service period during which any packets in a packet queue 120for the US at the AP can be sent to the US by the transceiver 116 underdirection of the processor 118. The AP processor 118 will direct thetransceiver 116 to respond with a frame containing voice packets fromthe packet queue 120, with the “end of service period” mark if there isonly one packet in the queue which ends the service period. The US canthen respond with an acknowledgement. Of course, there can be many morecontrol communications being exchanged which are not relevant to thepresent invention and therefore not described for the sake of brevity.The number of packets sent in a frame can be pre-negotiated between theaccess point and user station. Typically, a maximum of two voice packetsare sent in one service period, but this can be pre-negotiated to befour, six, or an unlimited number of voice packets allowed by theparticular communication interface (e.g. IEEE 802.11). If thepre-negotiated limit is unlimited, then the last packet transmitted mustbe marked with the “end of service period” mark.

The US processor 112 stores voice packets received by the transceiver110 from the AP 102 in a jitter buffer 114. The jitter buffer purposelydelays the received packets (for about 180 ms) in order to minimizedelay variations in the delivery of packets from the communicationnetwork 104, so that a user of the device 100 experiences voicecommunications with very little latency. A jitter buffer can include ahigh water mark and low water mark. A jitter buffer that is full to thehigh water mark should guarantee continuous voice communication withoutaudio gaps. The low water mark describes a timing point where audio inthe user device will be cutoff, which is to be avoided. The high watermark is achieved when the network latency is low. The low water mark isachieved when the network latency is high. If the network latencyexceeds the jitter buffer's size, the low water mark will decrease tozero and it is possible that the US will starve for packets. The lowwater mark is a function of the initial setting of the jitter buffer,the variability of the delay in the network and the actual delay of thenetwork when the jitter buffer is first filled. The present inventionintroduces a new threshold in the jitter buffer which is generally lowerthan the low water mark, as will be detailed below.

Both the other party (e.g. AP) and US 100 can have periods where theirtransceivers 116 and 110 are not transmitting, i.e. silent voice. Inaddition, the US 100 could purposely be muted, which of course keeps thetransmitter from transmitting outgoing voice packets. The presentinvention provides different operations depending on whether the otherparty transmitting voice and/or the US are generating voice packets, aswill be detailed below.

Generally, the AP packet queue 120 will be accumulating packets 106 fromthe communication network 104 and other party approximately every twentymilliseconds while there are no voice packet transmissions from the US.

In the prior art, the responsibilities of the US when it is notgenerating any voice packets to send to the AP is to trigger a periodicdownload of queued packets from the AP, usually at the same interval aspackets are generated (typically twenty milliseconds) from thecommunication network 104. The trigger frame could include actual voicepackets from the user station or can be a null frame if the MS has novoice packets to send. However, when the US is not transmitting voicepackets, the present invention proposes that the US only trigger thedownload of packets queued at the AP when the jitter buffer 114 of theUS is nearly empty, i.e. below the new threshold. As used herein, the US“triggering” the sending of voice packets from the AP packet queueincludes any one or more of; sending a trigger frame including voicepackets, sending a null trigger frame with no voice packets, sending avoice packet in an access category of an IEEE 802.11 communicationsystem that triggers a download, going out of power save mode, andsending a power save poll (PS-Poll) such as is done in legacy devices.It is envisioned that other triggers may also be used.

Preferably, the newly defined threshold is set to a time period equal tothe time from when the US sends a trigger to when the US receivespackets from the AP in its jitter buffer. In effect, the processor 112of the US determines the amount of time needed to trigger a download ofone queued packet from the AP and triggers the download that amount oftime before the jitter buffer becomes empty. The threshold can be setempirically and dynamically depending on interface conditions, and istypically in the range of five milliseconds. For example, the thresholddetermination could take into account measurements of how busy thecommunication interface is, either determined locally or frominformation contained in the beacon or otherwise received from the AP.In particular, if the AP indicates that the medium is busy, the US wouldtrigger the download sooner than if the AP indicates the medium is idle.Alternatively, the threshold determination may be fixed, such as a fixedten milliseconds before the last voice packet has completed playbackfrom the jitter buffer.

Therefore, in one embodiment of the present invention, while the US isnot transmitting voice packets, such as in an Unscheduled AutomaticPower Save Delivery (U-APSD) mode, the US will send a trigger to obtainpackets from the packet queue of the AP when the available voice packetsin the jitter buffer fall below the threshold, i.e. the jitter buffer isnearly empty. It should be recognized that packets are queued up at theAP ready to be transferred to the US.

In an alternative embodiment, a legacy PS-Poll is used to trigger thedownload of packets from the AP. However, in accordance with the presentinvention, a PS-Poll is not needed after every packet is transmitted tothe AP, but only when the jitter buffer is nearly empty. This isadvantageous when the AP is able to bundle several packets into onelarger packet, as specified in IEEE 802.11 standards. In addition, thisalternative can be implemented independent of whether the device issending audio or not.

In another alternative embodiment, the trigger is based on heuristicsthat the US can use, such as channel activity measurements eithermeasured directly or issued in a beacon, whereupon the US can leave apower saving mode for a short period of time, at which point the AP willtransmit multiple-queued packets. When the last queued packet is sentfrom the AP, the AP will clear a “more data” field in a last packetdownload frame. After the last packet is sent, recognized as the “moredata” field being cleared, the US will transition back to power savemode. This alternative requires that the “more data” field be updatedcorrectly by the AP even if the non-AP station (e.g. US) is not in powersave mode. It is necessary in this case that the “more data” fieldalways reflects whether there is more data at an IEEE 802.11 operatingAP, not just when the corresponding non-AP station is in power savemode, but even when it is not in power save mode. The reason to useheuristics is that in conditions where the channel is busy it is notadvantageous for the US to go out of power save, while if the channel isidle, it is advantageous to use this particular technique.

In another embodiment, a proprietary extension is defined that allowsthe AP to bundle several standard real-time transport protocol (RTP)packets into a superpacket consisting of the RTP packets. This could beimplemented without relying on newer versions of the IEEE 802.11standard. In this way, only one trigger from the US will delivermultiple packets, which can be acknowledged by one blockacknowledgement, which results in battery savings.

In another embodiment, it should be noted that when one party is nottalking, the effect of audio delay is reduced. In this case, a (virtual)size of the jitter buffer is temporarily increased to improve thebattery savings by raising the maximum fill point of the jitter buffer.The changing of the jitter buffer size could be triggered by the use ofa mute button, or by some heuristics related to how often or how longthere are no voice transmissions seen on either side. For example, whenthere are no voice packets being transmitted in the receive stream, theUS could set an artificially high jitter buffer delay on that stream, adelay that exceeds the variability of packet arrivals. The US can lowerthis artificially high jitter buffer delay at the next time there are novoice packets being transmitted in that stream, as would be necessary inthe case where both parties are talking Similarly, having no voicepackets being transmitted in the receive stream would allow theartificially high jitter buffer delay to be implemented without anynoticeable audio gap, as an existing silent-voice based audio gap couldbe increased to the artificial level. Advantageously, by raising themaximum fill point of the jitter buffer, even fewer polls are needed toget packets from the AP.

When the other party device leaves mute, packets will start arriving.However, in accordance with the present invention the device will notstart playing the arriving packets until the delay plus the accumulatedtimes of the number of arriving packets equals the high water mark. Oncethe jitter buffer is nearly empty, the US can send another trigger wherea significant number of packets should be waiting at the AP. At thistime the (virtual) size of the jitter buffer can be reduced so as toapproach the high water mark.

In another embodiment, it is supposed that there are no voice packettransmissions from both the AP (other party) and US. Sending a triggerfor voice packets when the accumulated packet times in the jitter bufferreach some fraction, e.g. 70% but <=100%, of the jitter high water mark.In this mode, voice packets will not be sent to the US at every triggerfrom the US. In another embodiment, even when either of the AP and US istalking, the present invention can be implemented to reduce the numberof service periods to send packets to the US. In particular, the IEEE802.11 communication system defines particular access categories that donot trigger a download from the AP. A US can send voice packets usingone of the access categories that do not trigger a download from the AP.Then when the jitter buffer falls below the threshold, the US can switchthe sending of voice packets to an access category that does trigger adownload from the AP. In effect the switching of access categoriestriggers the sending of packets from the AP.

It should be noted that the threshold as defined herein for the presentinvention is not the same as the previously known low water mark forjitter buffers. The threshold is defined as the amount of time needed totrigger a download of one queued packet from the AP and triggers thedownload that amount of time before the jitter buffer is empty, and istypically 5 ms to 10 ms. In contrast, the low water mark is a functionof an initial network delay d, the initial jitter buffer setting s, andthe maximum delay of the network m, so it is s+d−m. If the initialjitter buffer is s=100 ms, the initial network delay is d=40 ms and themaximum network delay is m=80 ms, then the low water mark is 100+40−80,or about 60 ms. Any dynamic jitter buffer reductions are subtracted fromthis. Any audio gaps mean that the low water mark is going below zero,which is impossible, so after an audio gap, the low water mark is zeroIf the US is starving for packets, the present invention retains thenormal behavior of attempting to download packets every 20 ms.

FIG. 2 illustrates a flowchart of a method for inventory monitoringusing complementary modes for item identification, in accordance withthe present invention, wherein packets from a communication network areaccumulated 210 by an access point (AP). In general, the presentinvention is operable while the US transmitter is off 200, with theexception noted below.

The method includes defining 202 a jitter buffer threshold for thewireless communication device. The jitter buffer threshold is set equalto an amount of time to perform the sending 206, downloading 208, andadding 212 steps. Defining can further include re-negotiating toincrease the number of voice packets that can be sent in a serviceperiod. The re-negotiated number of voice packets could be a maximum fora wireless interface being used. Defining can also include temporarilyincreasing the size of the jitter buffer when there are no voice packetsbeing transmitted by either the user station and access point.

The method also includes determining 204 that an amount of packets inthe jitter buffer falls below the threshold.

The method also includes sending a trigger 206 to obtain queued voicepackets from an access point. The sending of a trigger include any oneor more of; sending a trigger frame including voice packets, sending anull trigger frame with no voice packets, sending a voice packet in anaccess category of an IEEE 802.11 communication system that triggers adownload, and sending a power save poll (PS-Poll) such as is done inlegacy devices. The trigger can also include the US leaving a powersaving mode due to channel activity measurements. Where the size of thejitter buffer has been increased, and when voice starts flowing in bothdirections again, triggering can include sending another trigger when ahigh water mark of the jitter buffer is reached, and reducing the sizeof the jitter buffer to approach the high water mark. In addition, whenthere are no voice packet transmissions from either of the AP and US,triggering includes sending a trigger for voice packets when theaccumulated packet times reach some predetermined fraction of the jitterhigh water mark.

The method also includes downloading 208 queued voice packets from theaccess point. Downloading can also include downloading multiple queuedpackets until a “more data” field is cleared in a download frame.

The method also includes adding 212 the voice packets from the accesspoint to the jitter buffer in the wireless communication device 100.

The method also includes acknowledging 214 the voice packets receivedfrom downloading. This can include one acknowledgement per packet, perservice period, or a block acknowledgement for multiple voice packetsreceived from downloading.

The present invention is applicable to battery-powered products usingpacket-delivered voice, where there is not a scheduled delivery ofpackets, which implies a requirement for a non-zero jitter buffer due tolatency problems in an IEEE 802.11 network. In particular, the presentinvention reduces the number of triggering frames needed to downloadedpackets from the AP. In cases where both parties in a conversation arein DTX, the number of packets transmitted and received can be reduced bya factor nearly corresponding to the number of packets for the highwater mark of the jitter buffer. Advantageously, the present inventionprovide power savings when a IEEE 802.11 user station is muted or in aDTX silence period by intelligent management of the local jitter buffer,as described above.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings.

The benefits, advantages, solutions to problems, and any element(s) thatmay cause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeatures or elements of any or all the claims. The invention is definedsolely by the appended claims including any amendments made during thependency of this application and all equivalents of those claims asissued.

Moreover in this document, relational terms such as first and second,top and bottom, and the like may be used solely to distinguish oneentity or action from another entity or action without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions. The terms “comprises,” “comprising,” “has”,“having,” “includes”, “including,” “contains”, “containing” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises, has,includes, contains a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus. An element proceeded by“comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . .a” does not, without more constraints, preclude the existence ofadditional identical elements in the process, method, article, orapparatus that comprises, has, includes, contains the element. The terms“a” and “an” are defined as one or more unless explicitly statedotherwise herein. The terms “substantially”, “essentially”,“approximately”, “about” or any other version thereof, are defined asbeing close to as understood by one of ordinary skill in the art, and inone non-limiting embodiment the term is defined to be within 10%, inanother embodiment within 5%, in another embodiment within 1% and inanother embodiment within 0.5%. The term “coupled” as used herein isdefined as connected, although not necessarily directly and notnecessarily mechanically. A device or structure that is “configured” ina certain way is configured in at least that way, but may also beconfigured in ways that are not listed.

It will be appreciated that some embodiments may be comprised of one ormore generic or specialized processors (or “processing devices”) such asmicroprocessors, digital signal processors, customized processors andfield programmable gate arrays (FPGAs) and unique stored programinstructions (including both software and firmware) that control the oneor more processors to implement, in conjunction with certainnon-processor circuits, some, most, or all of the functions of themethod and/or apparatus described herein. Alternatively, some or allfunctions could be implemented by a state machine that has no storedprogram instructions, or in one or more application specific integratedcircuits (ASICs), in which each function or some combinations of certainof the functions are implemented as custom logic. Of course, acombination of the two approaches could be used.

Moreover, an embodiment can be implemented as a computer-readablestorage medium having computer readable code stored thereon forprogramming a computer (e.g., comprising a processor) to perform amethod as described and claimed herein. Examples of suchcomputer-readable storage mediums include, but are not limited to, ahard disk, a CD-ROM, an optical storage device, a magnetic storagedevice, a ROM (Read Only Memory), a PROM (Programmable Read OnlyMemory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM(Electrically Erasable Programmable Read Only Memory) and a Flashmemory. Further, it is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choicesmotivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein will be readily capable of generating such softwareinstructions and programs and ICs with minimal experimentation.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed embodiment. Thus the following claims arehereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

1. A method for jitter buffer management for improved power savings in awireless communication device, the method comprising: defining (202) ajitter buffer threshold for the wireless communication device;determining (204) that an amount of packets in the jitter buffer fallsbelow the threshold; sending a trigger (206) to obtain queued voicepackets from an access point; downloading (208) queued voice packetsfrom the access point; and adding (212) the voice packets from theaccess point to the jitter buffer in the wireless communication device(100).
 2. The method of claim 1, wherein the jitter buffer threshold isset equal to an amount of time to perform the sending (206), downloading(208), and adding (212) steps.
 3. The method of claim 1, wherein whilethe wireless communication device is not transmitting voice packetsduring determining (204).
 4. The method of claim 1, wherein defining(202) can include re-negotiating to increase the number of voice packetsthat can be sent in a service period.
 5. The method of claim 4, whereinthe re-negotiated number of voice packets is a maximum for a wirelessinterface being used.
 6. The method of claim 1, further comprising thestep of acknowledging (214) the voice packets received from downloading.7. The method of claim 6, wherein acknowledging (214) includes sendingone block acknowledgement for multiple voice packets received fromdownloading.
 8. The method of claim 1, wherein sending a trigger (206)includes sending a power save poll.
 9. The method of claim 1, whereinsending a trigger (206) includes sending a frame in a particular accesscategory of an IEEE 802.11 communication system that triggersdownloading.
 10. The method of claim 1, wherein sending a trigger (206)includes the US leaving a power saving mode due to channel activitymeasurements, and downloading includes downloading multiple queuedpackets until a “more data” field is cleared in a download frame by theAP.
 11. The method of claim 1, wherein defining (202) includestemporarily increasing the size of the jitter buffer when there are novoice packets being transmitted by either the user station and accesspoint.
 12. The method of claim 11, wherein sending (206) includessending another trigger when a high water mark of the jitter buffer isreached, and reducing the size of the jitter buffer to approach the highwater mark.
 13. The method of claim 1, wherein when there are no voicepacket transmissions from either of the AP and US, sending (206)includes sending a trigger for voice packets when the accumulated packettimes in the jitter buffer reach some predetermined fraction of thejitter high water mark
 14. A user station (100) with improved powersavings using jitter buffer management, the user station comprising: ajitter buffer (114) having a defined threshold; a processor (112)coupled to the jitter buffer (114), the processor operable to determinethat an amount of packets in the jitter buffer falls below thethreshold; and a transceiver (110) coupled to the processor (112), thetransceiver operable under direction of the processor to send a triggerto obtain queued voice packets from an access point, and download thequeued voice packets from the access point, wherein the processor (112)adds the voice packets from the access point to the jitter buffer (114).